Furnace



jan. 20, 1925. 1,523,492

` w. B. REED vFURNACE Patented dan. 2G, 1925.

WILLrAMB. REED, or wnsrrrnnn, Massaonnsnrrs, AssIGNon. To 'THE H. B. SMITH COMPANY, or wEsTrIn-Ln, MASSACHUSETTS, A CORPORATION or MASSACHU- SETTS.

FURNACE.

Application filed October 8, 1923.

T all who-m it may concern.'

Beit known that I. VILLIAM B. REED, a citizen of the United States of America, and resident of 'Vestiield, in th-e county of Hampden and State of Massachusetts, have invented new and useful Improvements 'in Furnaces, of which the following is a specifi cation.

This invention vpertains to so-called smokeless furnaces, relating more particularly to furnaces for hot water and low pressure steam heating boilers.

The principal object of the invention is to improve the construction of such furnaces in the manner hereinafter more particularly described and pointed out in the claims.

In the accompanying drawings, a pre ferred embodimentof the invention is illustrated by way of example, and in such drawings Fig. 1 is a perspective view of a furnace embodying the present invention, a portion of its side wall being broken away to show details of the interior construction;

Fig. 2 is a rear end elevation'of the furnace, a portion of the rear wall being broken away;

Fig. 3 is a longitudinal vertical section through a furnace embodying the present invention, certain parts being shown in elevation;

Fig. 4 is a perspective of the base section of such a furnace, `the upper portion being removed;

Fig. 5 is a front elevation, partly in verticalsection, of a preheater device forming anelement'of the present invention;

Fig. 6 is a plan view of the device shown in Fig. 5; and

Fig. Tis a fragmentary vertical section to larger scale, of the upper part of one of the preheater tubes shown in Fig. 3.

Referring Vtothe drawings, the numeral 1 indicates -in general a furnace of usual construction but'emb'odying the novel features constituting' the present invention. This furnace comprises'the iire box 2, the grate 3, and theash pit 1- beneath the grate. At the rear of the -grate a bridge wall or fire back 5 of any usual construction :is arranged. This bridge wall is provided with one or more 'windows or openings 6 for the passage of the volatile or gaseous products of combastion.

Serial No. 667,091.

A combustion chamber 7 is located to the rear of the bridge wall or tire back Below the combustion chamb an airsupply pit, separate from the ash pit, or chamber' 8 is provi ded, This air supply pit or chamber is furnished with an air inl-et opening 9 in one of its walls controlled by a damper 10. Connections 11 extend from the damper to a handle 11"L conveniently located at the front of the furnace.

A metal plate 12 constituting' an clement of an air preheater separates the combustion chamber 7 from the vair supply chamber 8. This `plate preferably is turned up at its opposite edges 13 'and 14 respectively to provide a shallow, pan-like receptacle. A slab or layer 15 of fire-resistant material such, for example, as lire clay, sand. slag or the like is arranged upon the plate 12 to protect the latter from the intense heat of the combustion chamber.

The plate 12 is furnished with a series of openings or apertures. preferably adjacent to its forward edge and preferablydisposed in two parallel rows, although a greater or lesser number of rows of openings may be provided. The lower endof a tube 16of heat conducting material such for example as cast iron is disposed in each of the apertures in the plate 12, the lower ends of the tubes communicating freely with the air supply chamber 8. The top of each tube is furnished with one or more air deliveryv orifices 19, while the side walls of each tube near its upper end are provided with small orifices 20. These orifices in the end and sides of the tube are so designed that the principal `part of the 'air discharged is emitted near the extreme upper end of the tube.

A convenient construction illustrated in the drawings employs hollow caps 18 for closing the upper ends of theftubes. These caps are preferably of hexagonal contour so that they fit snugly against each other thus utilizing the available space to the best advantage and also keeping the tubes in proper relative position, and are furnished with downwardly extending nipples 18a which fit within the tubes.

The orifices 19 are formed in the `upper wall of the hollow cap and also in taperin bosses 18b projecting therefrom. Additiona orifices `19a are Vprovided in the lower wall of the cap if desired. While hexagonal ,oxygen to burn it.

caps are desirable for the purpose, it is contelnplated that apertured closures of other forni may be employed, or that a unitary header may be provided for the entire series of tubes, but in all cases it is desirable to stagger orifices in the ends of adjacent tubes.

The preheater unit thus constructed is positioned within theV combustion chamber in the manner indicated in Fig. 3, so that the bank of tubes 1G is disposed substantially parallel to the bridge wall 5 and with the air delivery apertures substantially at the level of the windows or openings 6 in the bridge wall.

In a furnace, part of the combustion takes place in the fire bed upon the grate and part in the combustion space or chamber. The burning fuel bed acts as a gas producer or retort wherein a portion of the solid fuel is distilled. The gases rising from the fuel bed thus contain a high percentage, varying according' be the fuels supplied, of volatile combustible with insufficient free Hence to burn these gases completely and eliminate smoke, air

' must be admitted and mixed with the volatile or gaseous combustible. The necessary amount of air for complete combustion can not be supplied through the grate, as the rate at which gas is evolved from the coal in the fuel bed increases in direct proportion to the amount of air passing through the grate, the amount of unconsumed combustible in the gases rising from the fuel bed remaining substantially the same, and if the great volume of air necessary for complete combustion be admitted over the fuel bed Vby opening the lire doors or leaving the dampers in such doors open the heating surfaces of the boiler are rapidly cooled, greatly reducing the efiiciency of the boiler as a water heating' instrument.

In accordance with the present invention substantially uniform results and practically complete combustion of the gaseous constituents of fuel high in volatile matter are secured without requiring any especial skill on the part` of the fireman. In the device herein disclosed, the volatile products kof combustion rising from the bed of fuel upon the grate 3 pass rearwardly through the windows or openings 6 in the bridgewall 5 and swirl laterally and downwardly about the bank of pipes 16 which are thus highly heated and warm the air within them.

This heated air escapes through the apertures in the pipes in the form of a multitude of filament-like streams or jets into the upper part of the stream of gas passing over the bridge wall. As the incoming air7 although hot, is not as hot as such gas, the fine filaments of air emitted from the oriiices tend to descend through the gaseous stream and to mingle intimately with the latter so that the preheated atmospheric oxygen in'nnediaely unites with the gaseous combustible completely oxidizing the latter with the result that substantially no particles of carbon or soot remain. This action also produces an extremely high temperature in the combustion space 7 from which the incandescent gas flows through suitable passages provided between the heating pipes of the boiler, thus rapidly raising the temperature of the water. The eX- haust gases then pass through suitable iues, to the chimney. Y y

The preheating unit illustrated in 5 is of simple and durable construction, and relatively cheap to manufacture, so that its replacement if necessary is not a 'substantial item .in the cost of operation, while it is readily applicable to furnaces of other construction with but slight change. Y A

l/Vhile in the present instance the tubes 16 have been shown. as vertically disposed, it is contemplated that they may be arranged in some other manner and that a greater or lesser number of tubes may be employed as circumstances may' warrant.

I claim:

l. A furnace of low pressure type havingv a combustion chamber and an air inlet pit below it, an apertured metallic plate separating the chamber and pit, a coating of 'tire resistant material upon the upper` surface of the plate,V anda series of tubes each seated at its lower end in an aperture in the plate and opening into the air inlet pit, said tubes having air discharge orifices in their lateral walls adjacent to their upper ends.

2. In combination with a furnaceof low pressure type, an air preheater comprisingV a metallic plate havingits opposite edges bent upwardly, the plate having a series of apertures adjacent to one edge, a tube seated at one end in each of said apertures and provided with a plurality of small discharge orifices adjacent to its 'other end, and fire resistant material covering the plate between its upturned edges.

3. A furnace of low pressure type comprising a 'grate and an ash pit-.below it, a combustion chamber to the rear of the grate,

an apertured bridge wallA separating thev space above the grate from the combustion chamber, an air inlet pit tothe rear ofthe ash pit and separated therefrom, a metallic partition between the air inlet pit and combustion chamber, and airpreheating-m'eans` carried by the partition comprising a series of parallel, vertical metallic tubes closed at their upper ends and having orifices in the upper portions of their side walls and at their upper ends arranged toV deliver a plurality of jets of heated air into the combustion chamber.

4:. In combination with affurnace of low pressure type, an -air preheater'comprising a plurality of rows of tubes open at one end to an air inlet chamber, and caps closing?r the opposite ends of the tubes, said caps having discharge Vorifices therein, orifices of adjacent caps being' staggered.

5. In combination with a furnace, an air preheatei' comprisingI a plurality of rows of metallic tubes couiniunicating;l at one end With an air supply, and hexagonal caps closingthe opposite ends of the tubes, said caps engaging' one another to hold the tubes in proper relative position, the caps being provided with air delivery openings.

G. ln combination with a furnace, an air preheater comprisingl a roiv of tubes communicating` at one end ivit-h an air supply, and caps closing` the opposite ends of the tubes, the caps having air delivery orifices therein and the tubes having delivery orifices in their lateral Walls adjacent to the caps.

7. A. furnace of the low pressure type comprising a grate, a combustion chamber to the rear of the grate, a bridge Wall separating the grate and conibustion chamber, said Wall having apertures for the passage of heated gases, an air inlet chamber below the combustion chamber, a horizontal metallic partition separating` the air inlet and combustion chambers, heat insulating` material protecting' the upper surface of said partition, the latter having series of openings therethrough, tubes of heat conducting material having their lower ends seated in the respective openings, each tube having a plurality of orifices in the upper part of its side Wall, and a hexagonal cap closing` the upper' end of each tube, said caps being` of larger diameter than the tubes and having orices in their tops and also in their under sides Where they overlap the tubes, the caps of adjacent tubes eiipagirig` each other to hold the tubes in parallel relation.

Signed b v Ine at Westfield, Mass., this (lst) first day of October 1923.

WILLIAM B. REED. 

